1. Field of the Invention
The invention relates to electrical frequency responsive structures, and refers more specifically to a frequency band suppression circuit comprising a pair of coils related in diameter and/or pitch, one of which is positioned within the other axially to provide a predetermined capacitance and inductance between the coils responsive to a frequency band it is desired to suppress.
2. Description of the Prior Art
In the past, electrical frequency responsive circuits have been used in many fields to reduce interference with the operation of particular equipment by electrical signals of predetermined frequencies. Thus, interference with television reception by citizen band radio operators or amateur radio operators is a problem without frequency responsive structure at the input of the television, such as a frequency band suppression circuit tuned to suppress the particular band of frequencies causing interference, or such as a high frequency pass circuit for suppressing all frequencies below a lower television frequency.
Prior frequency responsive circuits have usually been constructed of separate coils and capacitors soldered together, which have then been connected across a pair of conductors such as the conductors in the usual television cable between the television antenna and receiver. In the simplest case, a frequency band suppression filter circuit is a series connected coil and capacitor tuned to a particular frequency which it is desired to suppress.
Such structure requires the soldering of separate elements, one of which must be variable if the circuit is not pre-tuned. Such filters often become elaborate and therefore expensive.